Explosive hole cutters



15, 1967 R. B. ENZIAN 3,335,664

EXPLOSIVE HOLE CUTTERS Filed June 8, 1966 4 Sheets-Sheet 1 INVENTOR. fay/flea e. 4 209 fit h; 3 'By% 1967 R. B. ENZIAN 3,335,664 I EXPLOSIVE HOLE CUTTERS Filed June a, 1966 4 Sheets-Sheet 2 I ma It 0;

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Aug. 15, 1967 R. B. ENZIAN EXPLOSIVE HOLE CUTTERS 4 Sheets-Sheet 3 Filed June 8, 1966 Aug. 15, 1967 R. B. ENZIAN 3,335,664

EXPLOS IVE HOLE CUTTERS Filed June 8, 1966 4 Sheets-Sheet 4 INVENTOR. 13/66 450 8- A/Z 091V United States Patent Ofiice ABSTRACT OF THE DISCLOSURE An annular and tubular explosive hole cutter with a flat end which is flanged radially outward with an annular groove in the flat end in which a linear shaped explosive is disposed facing toward the fiat end with the opposite ends of the linear shaped charged materially spaced apart and spaced apart detonating means disposed in the groove between the spaced ends of the shaped charge for detonating both ends of the shaped charge simultaneously by an electric firing circuit which is disposed in the groove between the spaced detonators and connected to the detonators in series. The tubular hole cutter is flanged outwardly to hold the shaped charge in position facing the side of a sheet metal tank containing a liquid under pressure and the annular tubular member forms a cylindrical liquid discharge outlet when the detonators are simultaneously detonated. The sheet metal of the tank extending between the spaced ends of the shaped charge is not cut and acts as a hinge to retain the portion of the sheet which is cut by the shaped charge connected to the sheet metal of the tank as it is swung out of the way by the liquid in the tank and will not become detached into the liquid outflow from the tank through the annular tubular member.

The invention described herein may be manufactured and used by or for the United States Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to explosive hole cutters, and more particularly to shaped charge explosive means for cutting holes or openings in steel plates, especially stainless steel, relatively thin plates, sheets or tanks, employing an interrupted substantially annular metal cutting shaped linear explosive charge, having for an object the interruption or limiting of the cutting by the charge of a predetermined portion only of a cut out disk or portion to provide an intact hinge-like or bendable connection be tween the sheet or plate and the cut out portion to retain the cut out portion or disk in intact connected relation to the sheet or plate.

The use of flexible linear shaped explosive charges to cut or sever stainless steel orother similar sheets or plate materials is well known. Also the use of annular high explosives which are fashioned with inverted annular V shape, facing plates to be cut or punched out by detonation of the shaped explosive charge is well known. One example thereof is the disclosure in US. Patent No. 2,407,- 093, dated Sept. 3, 1946, issued to Mohaupt. In this patent the detonation of the annular high explosive shaped charge is alleged to provide an annular high velocity cutting means or jet to penetrate varying thicknesses of sheet or target material depending upon the loading of the shaped annular explosive charge to cut out and form an annular opening in the sheet.

Also known is the fact that explosives commonly known as PETN or RDX, when fashioned in an inverted V v,shape and housed in lead sheathing, will, upon detonation,

cause fusion of the lead into a high velocity directed metal 3,335,654 Patented Aug. 15, 1967 cutting jet. This jet will penetrate varying thicknesses of sheet material depending upon the loading of the flexible linear shaped charge.

To obtain optimum cutting of a metal sheet a definite range of stand olf distance of the shape charge to the surface is established according to the loading and configuration of the explosive charge. The shaped explosive charge may be housed in a frangible, or non-frangible housing, according to the application desired. In addition to the cutting of the target plate or sheet, the force of the explosion from the shaped charged in the jet causes a bending of the adjacent material at the edge of the out unless there is back up material extending right up to the edges of the desired cutting area. Also, the cutting jet may carry or extend into the vessel or receptacle when it is closed by the sheet. When the sheet is backed up by liquid in the vessel the explosive products create a localized high pressure area in the vicinity of the cut.

In some previous sheet cutting operations utilizing flexible linear shaped charges for cutting holes and openings in stainless steel sheets and similar materials, the cut out portion or disk has been allowed to either go into the vessel or be ejected from the vessel. Successful attempts to retract the cut out disk back into a liquid holding vessel after the cut have proved to be very marginal. The pressure build up forces the cut out portion or disk outward, or against a restraining member which impairs the out ward flow from the receptacle or slows the retraction of the cut out portion. The cut out portion ordinarily cannot be allowed to be expelled from the vessel with its liquid contents because of potential blockage of liquid flow in the dissemination tube area for the contents of the receptacle because of potential damage to adjacent equipment supplied by the contents of the vessel which is released through the cut out portion.

A principal object of the invention is the provision of a method and means for retaining the cut out portion or disk while at the same time allowing instantaneous removal of the cut out portion or disk from the flow area formed by the cut out portion.

A further object is the provision of a flexible linear shaped explosive charge which extends only part way around the area or periphery of the portion to be cut out of a sheet so as to leave an intact bendable hinge-like portion located between the outer ends of the shaped explosive charge whereby the explosive pressure bending of the area adjacent to the cut, together with the localized pressure build up, causes the disk or cut out portion to hinge and swing outwardly, out of the way about the uncut hingelike portion.

A further object is the provision of an annular support having an annular channel formed therein containing a linear explosive shaped charge facing outward and extending linearly only part way around the channel so as to leave a predetermined linear space in the channel between the opposite extremities of the shaped charge and means for detonating the shaped charge while the annular support is fixed against the metallic sheet material with the channel and shaped charge facing the sheet material.

A further object is the provision of a linear explosive shaped charge means formed to cut out a major portion of an opening in a metallic sheet and leave a minor intact portion between the ends of the cut portion to provide a bendable hinge-like connection between the sheet and the portion cut out by detonation of the shaped linear explosive charge.

Other objects and advantages of the invention will become apparent from the following description and accompanying drawings in which like reference characters refer to like parts in the several figures.

In the drawings:

FIGURE 1 is a perspective view of an explosive hole cutter incorporating the invention, as applied to a fluid or liquid tank or container, part of the container being broken away and shown in section.

FIGURE 2 is a plan view of the explosive hole cutter shown in FIGURE 1 looking toward the shaped linear explosive charge, parts being broken away and shown in section.

FIGURE 3 is a transverse sectional view taken about on line 2-2 in FIGURE 2, looking in the direction of the arrows.

FIGURES 4, 5, 6 and 7 are somewhat schematic sectional views progressively illustrating the action of the shaped explosive charge on the cut out portion of the metallic sheet; for instance, when the invention is applied to a stainless steel tank or receptacle containing a liquid under pressure. In these views a form of retaining or securing means is shown in dotted lines as an annular flange.

FIGURE 8 is a schematic view showing the flexible linear shaped charge explosive with electric detonators at the opposite ends thereof including an electric firing circuit and means for shorting out the circuit to prevent accidental detonation.

FIGURE 9 is an enlarged sectional view taken through a typical mounting ring or annular support, for instance on line 9-9 of FIGURE 2, to more clearly illustrate the annular groove with the shaped charge located in a lead or plastic backing or potting material in the receiving channel prior to detonation.

Referring more particularly to FIGS. 1 and 3, the reference numeral 1 denotes a receptacle, for instance a closed liquid container or tank made of stainless steel sheet material containing a liquid 2 under pressure which is to be discharged therefrom through one side of the receptacle. The tank or receptacle 1 may be of any size and shape, however, as shown, it is rectangular; a portion thereof being broken away and shown in section.

The reference numeral 3 denotes one side or face of the receptacle 1 with the invention applied thereto as indicated generally at 4 for cutting a discharge opening therein for the discharge of the liquid or contents through the opening.

The invention comprises a basic metal housing in the form of an annular ring or frame 5, preferably, but not necessarily, rectangular in cross section, as seen in FIGS. 3 to 7 and 9. The ring or housing 5 is formed with an annular channel 6 in one side thereof disposed to face the outer surface of the side 3 of the container 1. The frame or ring 5 at the inner and outer sides 6a6b of the channel 6 is preferably in intimate contact with the surface 3 of the container 1.

The ring or annular frame 5 is shown as circular, although it may be substantially rectangular, or even polygonal in plan and made of iron, steel, or any other suitable material or alloy. Also any suitable means may be provided for securing the ring 5 against the outer surface 3 of the receptacle 1. For instance, as shown, the ring or frame 5 may be provided with an outwardly projecting annular flange 7 which is secured to the plate 3 by any conventional means such as screw fasteners or bolts 8, or even welded, to prevent leakage between the surface 3 and ring 5 when the opening in the plate or sheet 3 is formed. The flange 7 may be provided with an annular back up ring 9 located inside the tank 3 to receive the screw fasteners 8.

A suitable plastic backing material or potting compound 10 is disposed in the channel 6 and a flexible linear shaped charge explosive 11 is disposed in the channel 6 with the V thereof facing outwardly toward the face 3 of the tank, and disposed in the desired spaced facing relation to the surface 3.

The linear shaped explosive charge 11 as shown in FIGS. 2 and 8 extend only part way around the channel .4 6, as indicated at A in FIG. 2, with electric detonator means 12 and 13 for the shaped charge located at the opposite ends of the shaped charge.

The channel portion B between the detonators 12 and 13 does not contain an explosive charge but contains the electric conductors 14 and 15 which are connected to the detonators 12 and 13 for firing the shaped charge in the area A portion when the electrical circuit, for instance, as disclosed in FIG. 8, is closed. As shown, the detonators 12 and 13 are connected in series by conductors 12a and 13a through a suitable disconnect plug 16, firing circuit 17, battery or electrical source 18, and firing control switch 21.

Means may be provided for short-circuiting the firing circuit when the plug 16 is disconnected as indicated at 22 in FIG. 8 including a switch 23.

If desired, the circuit wires 12a-13a may be metallically shielded as indicated at 24 which is grounded at 25 to provide further safety against accidental excitement of the circuit 12a-13a.

The potting compound 10 in the channel 6 retains the shaped linear charge 11 in properly spaced inward relation facing outwardly in the channel 6 as shown in FIG. 9, and the potting compound 10 may be a lead or other suitable composition.

If desired a dissemination tube or conduit such as indicated at 26 in FIG. 1 may be provided.

The annular support or ring 5 is preferably formed with a bore or opening 27 extending into the portion B of the channel 6 for bringing the electric conductors 12a and 13a therethrough from the back to connect the conductors 14 and 15 which connect the detonators 12 and 13.

Briefly describing the operation, the ring 5 is secured against the tank 3 containing a liquid 2 under pressure adapted to be discharged.

When the firing circuit is closed by the switch 21 the detonators 12 and 13 explode the shaped charge 11 as indicated in FIG. 4 and the force of the shaped charge 11 between the detonators 12 and 13 projects a burning jet through the sheet 3 in the area A to leave a partially cut out portion 3a with an uncut portion 3b which forms a hinge-like portion between the locations of the detonators 12 and 13 or substantially across the area indicated at B in FIG. 2.

The force of the cutting jet bends the edges of the cut out portion 3a inwardly into the receptacle as indicated at 3c. The pressure of the liquid within the tank plus the pressure increase due to the explosion of the shaped charge 11 entering the tank 1 forces the cut out hinged portion 3a outwardly as is progressively shown in FIGS. 4 to 7 to a retained position out of the way of the discharge of the liquid from the tank. The intact uncut or hinge portion 3b thus retains the cut out portion attached disk 3a as seen in FIG. 7 while permitting full and complete discharge through the cut out opening surrounded by the ring 5, the cut out disk portion 3a swinging laterally out of the way, for instance against the inside of the liquid dissemination conduit or tube 26 to prevent damage to adjacent equipment.

For purposes of exemplification a particular embodiment of the invention has been shown and described to the best understanding thereof. However, it will be apparent that changes and modifications of the arrangement of the parts thereof may be resorted to without departing from the true spirit and scope of the invention as defined in the accompanying claims.

I claim:

1. An explosive hole cutter for sheet metal comprising an annular tubular supporting frame having a continuous annular channel formed in one face thereof between the inner and outer peripheries of the frame adapted to face the sheet metal to be cut and surround the area to be cut in the sheet, a linear explosive shaped charge disposed in said channel facing outwardly in predetermined inwardly spaced relation to the outer edges of said channel with the opposite ends of the charge materially spaced apart, and separate detonating means in said channel at intermediate said opposite ends of said linear explosive spaced charge connected for simultaneously detonating the shaped charge from both ends While said frame is disposed in contacting relation with the sheet to be cut by the shaped charge to leave an un-cut hinge-like portion in the sheet extending between the spaced ends of the cut portion.

2. A device as claimed in claim 1 in which the channel formed in the frame is circular and extends around the frame between the inner and outer peripheries thereof and said linear explosive shaped charge is disposed in said channel with the opposite ends of the linear shaped charge disposed in said channel in materially spaced linear relation to each other, with said detonators dis posed in said channel in spaced relation to each other at the ends of the shaped charge to provide an uncut hinge-like portion in the sheet between the ends of the spaced charge when the shaped charge is fired while the frame is in surface contact with the sheet, for retaining the cut out area of the sheet opposite the location of shaped charge connected to the sheet by the hinge-like portion.

3. An explosive hole cutter for sheet material as set forth in claim 2 in which said detonators are electrically detonated simultaneously, and includes a firing circuit connecting said detonators in series disposed in said channel between said detonators for simultaneously firing said detonators to explode said linear shaped charge simultaneously from both ends thereof.

4. In an explosive sheet opening cutter for sheet metal tanks containing a liquid under pressure comprising a cylindrical metallic ring having a flat end surface contact with the surface of the tank to be cut to form the liquid outlet opening, radially extending annular flange means on said ring for supporting said ring with said flat end surface in contact with said sheet, a circular concentric groove formed in said ring in the flat sheet contacting end thereof, a linear explosive shaped charge disposed in said groove facing outwardly toward said end with the opposite ends of the shaped charge in said groove disposed in materially spaced relation to each other to leave a material portion of said groove between the ends of the shaped charge without an explosive therein, electric detonators in said groove between said ends of said shaped charge connected for simultaneously firing the shaped charge from the opposite ends thereof, an electric firing circuit extending into said groove connecting the detonators in series between the detonators for simultaneously firing said detonators to explode said linear shaped charge from both ends thereof.

BENJAMIN A. BORCHELT, Primary Examiner. V. R. PENDEGRASS, Assistant Examiner.

8/ 1951 Great Britain. 

1. AN EXPLOSIVE HOLE CUTTER FOR SHEET METAL COMPRISING AN ANNULAR TUBULAR SUPPORTING FRAME HAVING A CONTINUOUS ANNULAR CHANNEL FORMED IN ONE FACE THEREOF BETWEEN THE INNER AND OUTER PERIPHERIES OF THE FRAME ADAPTED TO FACE THE SHEET METAL TO BE CUT AND SURROUND THE AREA TO BE CUT IN THE SHEET, A LINEAR EXPLOSIVE SHAPED CHARGE DISPOSED IN SAID CHANNEL FACING OUTWARDLY IN PREDETERMINED INWARDLY SPACED RELATION TO THE OUTER EDGES OF SAID CHANNEL WITH THE OPPOSITE ENDS OF THE CHARGE MATERIALLY SPACED APART, AND SEPARATE DETONATING MEANS IN SAID CHANNEL AT INTERMEDIATE SAID OPPOSITE ENDS OF SAID LINEAR EXPLOSIVE SPACED CHARGE CONNECTED FOR SIMULTANEOUSLY DETONATING THE SHAPED CHARGE FROM BOTH ENDS WHILE SAID FRAME IS DISPOSED IN CONTACTING RELATION WITH THE SHEET TO BE CUT BY THE SHAPED CHARGE TO LEAVE AN UN-CUT HINGE-LIKE PORTION IN THE SHEET EXTENDING BETWEEN THE SPACED ENDS OF THE CUT PORTION. 